1. Field of the Invention
The present invention relates to a power load control system suitable for collective housing such as apartments.
2. Description of the Related Art
A distribution system, in which power is received collectively at a high voltage, for example, at 6000 V and is distributed to individual households at low voltage (100V or 200V), is employed in collective housing such as apartments. The following differences are considered between a system in which power is received at a low voltage by each household and a system which power is received collectively at a high voltage and is distributed at low voltage to each household.
FIG. 1 is a schematic view illustrating one example that power is supplied to a house, wherein power is distributed in a house 201 through a breaker at low voltage (100 V or 200 V) from a power system 200 of a distribution company. The contract capacity is determined on the basis of a maximum power capacity. The maximum power capacity is determined by assuming a case that appliances which consume large amount of power such as a TV, an air conditioner, a rice cooker, a washing machine, and a refrigerator are used at the same time. For example, the contract capacity when these appliances are used at the same time is generally determined to be 3 kVA. Available power capacity (VA) is determined in a contract with the distribution company.
Usually, the contact is made on the basis of the power capacity (VA) when the load in the house is used at maximum, and a breaker suitable for that power capacity is equipped by the power distribution company.
FIG. 2 is a schematic view illustrating one example of a system for collectively receiving at a high voltage and distributing at a low voltage which is used for distributing from a power distribution company to collective housing such as apartments. Power is collectively received at a receiving equipment 300 equipped with collective housing at a high voltage such as 6000 V from the power distribution company and the power is distributed from the receiving equipment 300 to each household 13a, 13b . . . 13n at a low voltage (100 V or 200 V). The power is converted to a low voltage by the receiving equipment 300, and is supplied to the households 13a, 13b . . . 13n through a breaker 130 equipped with each of the households 13a, 13b . . . 13n. A load 131 in each of the households 13a, 13b. . . 13n is driven by the supplied power.
FIG. 3 is a diagram for comparing power amounts used in a month and electricity bills in a collective high voltage receiving and low voltage receiving. As shown in FIG. 3, a base rate of the low voltage receiving is small as compared with of the collective high voltage receiving and little depends on the contract capacity. On the other hand, the bill in the high voltage receiving becomes smaller as the contract capacity becomes small.
In the cases (1) and (2) of FIG. 3, the base rate is about 2000 yen and 1300 yen respectively.
An electricity bill in total is a sum of the base rate and usage-based charge in both of the cases. In the low voltage receiving, usage-based charge per kWh is large. In addition, in the bill system of the low voltage receiving, the usage-based charge per kWh increases when used amount exceeds a certain level.
On the other hand, in the high voltage collective receiving, the charge per kWh is smaller than that in the low voltage receiving, and even when the usage amount increases, the charge per kWh does not change. It is noted that the charge per kWh changes depending on seasons, and the charge per kWh changes depending on time in three levels when a time-varying charge contract is made. As shown in FIG. 3, electricity bills in the high voltage collective receiving (the case (1)) and the low voltage receiving are balanced at the A point.
In the high voltage collective receiving, the electricity bill is smaller when the contract capacity is small.
In collective housing, however, a receiving equipment for an excessive contract capacity is employed in assuming such a case that high load electrical appliances such as air conditioners are being operated at the same time.
The present invention was made to solve the above problem and provide a system for reducing receiving power capacity without user inconvenience and discomfort in collective housing or the like.
A power load control system according to the present invention comprises a plurality of high load electrical appliances and a power control unit connected with the plurality of high load electrical appliances. The power control unit controls operation of the plurality of high load electrical appliances together.
The power control unit controls the plurality of high load electrical appliances to operate in time or alternately.
As a result, concentration of operation of the high load electrical appliances can be prevented and a peak electric current can be greatly reduced.
The plurality of high load electrical appliances are divided into n groups, and the power control unit controls to prohibit the high load electrical appliances in one to nxe2x88x921 of the n groups from starting operation for a certain time and to allow the high load electrical appliances in the rest of the groups to start and continue operation, and repeats to control periodically so as to ensure that one to nxe2x88x921 of the n groups are prohibited from starting operation.
The high load electrical appliances which, once started to operate, can continue to operate even when they are in a group which is prohibited from starting operation. A high load electrical appliance generally requires a large current at starting. Thus, when the appliances are controlled at starting, a peak electric current can be greatly reduced. When taking an air conditioner as an example, an air conditioner which once started operation can continue to operate even when it is in a group which is prohibited from the starting operation. A peak electric current can be greatly reduced when an air conditioner is controlled at starting because an air conditioner requires a large current at starting. Operation after starting does not matter in order to reduce a peak current. Furthermore, when an air conditioner which once started operation stops, an user may feel uncomfortable. Therefore, it is better that an air conditioner which started operation continues to operate.
The plurality of high load electrical appliances are divided into n groups, and the power control unit controls the electrical appliances in one to nxe2x88x921 of the n groups to output 100% and the electrical appliances in the rest of the groups to output less than 100%, and changes an output percentage cycle periodically. As a result, every high load electrical appliance can be operated while total power consumption is suppressed without making users feel uncomfortable.
A power load control system according to the present invention comprises a system for collectively receiving at a high voltage by receiving equipment equipped in collective housing and distributing at a low voltage from the receiving equipment to each of households in the collective housing, high load electrical appliances equipped in the households, and a power control unit connected with each of the high load electrical appliances. The power control unit controls operation of the high load electrical appliances together.
The collective housing refers to an apartment, a dormitory, or a group of a plurality of detached houses.
The power control unit controls the high load electrical appliances to operate in time or alternately.
The households in the collective housing are divided into (n) groups, the power control unit controls to prohibit the high load electrical appliances in one to nxe2x88x921 of the n groups from starting operation for a certain time and allow the high load electrical appliances in the rest of the groups to start and continues operation, and repeats to control periodically so as to ensure that one to nxe2x88x921 of the n groups are prohibited from starting operation.
The households in the collective housing are divided into n groups, the power control unit controls the high load electrical appliances in one to nxe2x88x921 of the n groups to output 100% and the electrical appliances in the rest of the groups to output less than 100%, and changes an output percentage cycle periodically.
The high load electrical appliances are linked with the power control unit via a wired or wireless communication line.
With the above constitution, power used at a peak can be suppressed. Thus, in the collective housing or the like, a total contract capacity and a base rate can be reduced.